History

Adult hydronephrosis and hydroureter

Symptoms vary depending on whether the hydronephrosis is acute or chronic.

With acute obstruction, pain is frequently present, due to distention of the bladder, collecting system, or renal capsule. Pain is typically minimal or absent with partial or slowly developing obstruction (as with congenital ureteropelvic junction [UPJ] obstruction or a pelvic tumor). It is not uncommon, for example, to see an adult who is noted to have hydronephrosis due to previously unsuspected UPJ obstruction.

In comparison, relatively severe pain (renal or ureteral colic) may be seen with acute complete obstruction (as with a ureteral calculus) or when acute dilatation occurs after a fluid load that increases the urine output to a level greater than the flow rate through the area of obstruction. An example of the latter problem occurs after beer drinking in a college student with previously asymptomatic and unsuspected UPJ obstruction.

The site of obstruction determines the location of pain. Upper ureteral or renal pelvic lesions lead to flank pain or tenderness, whereas lower ureteral obstruction causes pain that may radiate to the ipsilateral testicle or labia.

With regard to renal insufficiency, patients with complete or severe partial bilateral obstruction also may develop acute or chronic renal failure. In the latter setting, the patient is often asymptomatic and the urinalysis results may be relatively normal or reveal only a few white or red blood cells.
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Anuria may be a presenting symptom of the patient. Although the urine volume could be reduced in any form of renal disease, anuria is most often seen in 2 conditions: complete bilateral urinary tract obstruction and shock. Other less common causes of anuria are hemolytic-uremic syndrome, renal cortical necrosis, bilateral renal arterial obstruction, and crescentic or rapidly progressive glomerulonephritis, particularly anti–glomerular basement membrane (GBM) antibody disease. Bilateral symmetrical hydronephrosis usually suggests a cause related to the bladder, such as retention, prostatic blockage, or severe bladder prolapse.

Considerations include the following:

A history of hematuria may herald a stone or malignancy anywhere in the urinary tract

A history of fever or diabetes adds urgency to the evaluation and treatment

Hydronephrosis in a patient with a solitary kidney is an emergent situation

Hydronephrosis may develop silently, without symptoms, as the result of advanced pelvic malignancy or severe urinary retention from bladder outlet obstruction.

Pediatric hydronephrosis and hydroureter

Fetal hydronephrosis is a readily diagnosed finding on antenatal ultrasound examination and can be detected as early as the 12th to 14th week of gestation.
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Although renal pelvic dilatation is a transient, physiologic state in most cases, urinary tract obstruction and vesicoureteral reflux (VUR) are also causal. Most cases of antenatal hydronephrosis are not clinically significant and can lead to unnecessary testing of the newborn baby and anxiety for patients and healthcare providers.

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Physical

Physical findings include the following:

With severe hydronephrosis, the kidney may be palpable.

With bilateral hydronephrosis, lower extremity edema may occur. Costovertebral angle tenderness on the affected side is common.

A digital rectal examination should be performed to assess sphincter tone and to look for hypertrophy, nodules, or induration of the prostate.

In children, the physical examination, especially in a newborn, can help detect abnormalities that suggest genitourinary abnormalities associated with antenatal hydronephrosis. These include the following:

The presence of an abdominal mass could represent an enlarged kidney due to obstructive uropathy or multicystic dysplastic kidney (MCDK).

A palpable bladder in a male infant, especially after voiding, may suggest posterior urethral valves.

A male infant with prune belly syndrome will have deficient abdominal wall musculature and undescended testes. The presence of associated anomalies should be noted.

The presence of outer ear abnormalities is associated with an increased risk of congenital anomalies of the kidney and urinary tract (CAKUT).

A single umbilical artery is associated with an increased risk of CAKUT, particularly VUR.

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Causes

A multitude of causes exist for hydronephrosis and hydroureter. Classification can be made according to the level within the urinary tract and whether the etiology is intrinsic, extrinsic, or functional.

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors Srinivas Vourganti, MD, Prakash Maniam, MD, and martin I Resnick, MD, to the development and writing of this article.